JDK自带HttpServer处理Http请求

秒速五厘米 2023-03-02 05:14 12阅读 0赞

下面是JDK自带的HttpServer处理Http请求的源码和流程，我看网上貌似还没有介绍这个的流程，所有就画了一下，如有不足，请矫正。

### 1、官方API ###

[https://docs.oracle.com/javase/7/docs/jre/api/net/httpserver/spec/com/sun/net/httpserver/HttpExchange.html][https_docs.oracle.com_javase_7_docs_jre_api_net_httpserver_spec_com_sun_net_httpserver_HttpExchange.html]

### ![20200727220002884.png][] ###

### 2、启动一个HttpServer demo: ###

<table> 
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 <td> <code>private</code>&nbsp;<code>static</code>&nbsp;<code>final</code>&nbsp;<code>Map&lt;String, HttpHandler&gt; routeMap =&nbsp;</code><code>new</code>&nbsp;<code>HashMap&lt;String, HttpHandler&gt;();</code> &nbsp; <code>// 配置要创建的Context, key为请求的路径，value为请求的处理器，AgentServerHandler是实现HttpHandler接口，重写handle方法，处理自己的逻辑；</code> <code>static</code>&nbsp;&nbsp;<code>{ </code> <code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code><a href="https://wiki.youjiayoubao.cn/display/RD/2020/07/27/routeMap.put%28" rel="nofollow">routeMap.put(</a></code><code>"/agent/server"</code><code>,&nbsp;</code><code>new</code>&nbsp;<code>AgentServerHandler());</code> <code>}</code> &nbsp; <code>public</code>&nbsp;<code>static</code>&nbsp;<code>void</code>&nbsp;<code>main(String[] args)&nbsp;</code><code>throws</code>&nbsp;<code>Exception{ </code> <code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>String port =&nbsp;<a href="https://wiki.youjiayoubao.cn/display/RD/2020/07/27/PropertiesHelper.getProperty%28" rel="nofollow">PropertiesHelper.getProperty(</a></code><code>"<a href="https://wiki.youjiayoubao.cn/display/RD/2020/07/27/server.port" rel="nofollow">server.port</a>"</code><code>,&nbsp;</code><code>"20200"</code><code>);</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code><a href="https://wiki.youjiayoubao.cn/display/RD/2020/07/27/HttpServer.create%28%29;" rel="nofollow">HttpServer.create();</a></code> <code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>// 绑定地址，端口，请求队列； 队列设置成0则使用默认值：50</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>HttpServer server =&nbsp;<a href="https://wiki.youjiayoubao.cn/display/RD/2020/07/27/HttpServer.create%28" rel="nofollow">HttpServer.create(</a></code><code>new</code>&nbsp;<code>InetSocketAddress(<a href="https://wiki.youjiayoubao.cn/display/RD/2020/07/27/Integer.parseInt%28port%29%29," rel="nofollow">Integer.parseInt(port)),</a>&nbsp;</code><code>0</code><code>);</code> &nbsp; <code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code><a href="https://wiki.youjiayoubao.cn/display/RD/2020/07/27/logger.info%28" rel="nofollow">logger.info(</a></code><code>"Loading&nbsp;<a href="https://wiki.youjiayoubao.cn/display/RD/2020/07/27/route..." rel="nofollow">route...</a>"</code><code>);</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>for</code>&nbsp;<code>(String keySet :&nbsp;<a href="https://wiki.youjiayoubao.cn/display/RD/2020/07/27/routeMap.keySet%28%29%29" rel="nofollow">routeMap.keySet())</a>&nbsp;{ </code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>// 可以创建多个Context,每个key对应一个Handler;</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code><a href="https://wiki.youjiayoubao.cn/display/RD/2020/07/27/server.createContext%28keySet," rel="nofollow">server.createContext(keySet,</a>&nbsp;<a href="https://wiki.youjiayoubao.cn/display/RD/2020/07/27/routeMap.get%28keySet%29%29;" rel="nofollow">routeMap.get(keySet));</a></code> <code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>}</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>// 配置HtteServer请求处理的线程池，没有配置则使用默认的线程池；</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code><a href="https://wiki.youjiayoubao.cn/display/RD/2020/07/27/server.setExecutor%28YjThreadPool.build%28%29%29;" rel="nofollow">server.setExecutor(YjThreadPool.build());</a></code> <code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code><a href="https://wiki.youjiayoubao.cn/display/RD/2020/07/27/server.start%28%29;" rel="nofollow">server.start();</a></code> <code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code><a href="https://wiki.youjiayoubao.cn/display/RD/2020/07/27/logger.info%28" rel="nofollow">logger.info(</a></code><code>"Server have been started. Listen to port: "</code>&nbsp;<code>+ port);</code> <code>}</code> </td> 
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</table>

Context 可以创建多个，核心思想：HttpServer将path和Handler处理器封装成 HttpContextImpl 对象，然后复制给ServerImpl的属性contexts, 其实就是一个链表；

<table> 
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 <td> <code>class</code>&nbsp;<code>ContextList { </code> <code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>static</code>&nbsp;<code>final</code>&nbsp;<code>int</code>&nbsp;<code>MAX_CONTEXTS =&nbsp;</code><code>50</code><code>;</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>LinkedList&lt;HttpContextImpl&gt; list =&nbsp;</code><code>new</code>&nbsp;<code>LinkedList();</code> &nbsp; <code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>ContextList() { </code> <code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>}</code> &nbsp; <code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>public</code>&nbsp;<code>synchronized</code>&nbsp;<code>void</code>&nbsp;<code>add(HttpContextImpl var1) { </code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>assert</code>&nbsp;<code><a href="https://wiki.youjiayoubao.cn/display/RD/2020/07/27/var1.getPath%28%29" rel="nofollow">var1.getPath()</a>&nbsp;!=&nbsp;</code><code>null</code><code>;</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>this</code><code><a href="https://wiki.youjiayoubao.cn/display/RD/2020/07/27/.list.add%28var1%29;" rel="nofollow">.list.add(var1);</a></code> <code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>}</code> <code>}</code> &nbsp; &nbsp; <code>public</code>&nbsp;<code>synchronized</code>&nbsp;<code>HttpContextImpl createContext(String var1, HttpHandler var2) { </code> <code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>if</code>&nbsp;<code>(var2 !=&nbsp;</code><code>null</code>&nbsp;<code>&amp;&amp; var1 !=&nbsp;</code><code>null</code><code>) { </code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>HttpContextImpl var3 =&nbsp;</code><code>new</code>&nbsp;<code>HttpContextImpl(</code><code>this</code><code>.protocol, var1, var2,&nbsp;</code><code>this</code><code>);</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>// 将path和Handler封装在var3中，add到contexts链表中；</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>this</code><code><a href="https://wiki.youjiayoubao.cn/display/RD/2020/07/27/.contexts.add%28var3%29;" rel="nofollow">.contexts.add(var3);</a></code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>this</code><code><a href="https://wiki.youjiayoubao.cn/display/RD/2020/07/27/.logger.config%28" rel="nofollow">.logger.config(</a></code><code>"context created: "</code>&nbsp;<code>+ var1);</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>return</code>&nbsp;<code>var3;</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>}&nbsp;</code><code>else</code>&nbsp;<code>{ </code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>throw</code>&nbsp;<code>new</code>&nbsp;<code>NullPointerException(</code><code>"null handler, or path parameter"</code><code>);</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>}</code> <code>}</code> &nbsp; &nbsp; <code>removeContext 操作实质就是从LinkedList中取元素；</code> </td> 
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</table>

### HttpServer处理Http请求的流程 ###

流程图如下：

![20200727220059551.png][]

1、创建线程，从线程池中获取空闲的线程，如果没有则创建，等线程池那一套， task.run();

2、ServerImpl的一个内部类Exchange实现了Runnable接口，在run方法里面执行部分逻辑；Exchange有一下几个重要的属性：

<table> 
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 <td> <code>SocketChannel chan;</code> <code>HttpConnection connection;</code> <code>HttpContextImpl context;</code> <code>InputStream rawin;</code> <code>OutputStream rawout;</code> <code>String protocol;</code> <code>ExchangeImpl tx;</code> <code>HttpContextImpl ctx;</code> <code>boolean</code>&nbsp;<code>rejected =&nbsp;</code><code>false</code><code>;</code> </td> 
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</table>

大致逻辑如下

1、首先获取上下文对象，判断上下文是否为空，如果context不是空，则初始化 rawin和rawout，从connection对象的输入输出流中获取；

2、如果上下文是空的，则在SocketChannel中获取数据，初始化rawin和rawout；

3、根据获取的rawin和rawout创建一个Request对象，去判断Request对象的requestLine是否为空，如果是空的，则关闭当前链接，直接返回；

4、如果requestLine不是空，则去校验requestLine的合法性，如果requestList不合法，直接抛400异常Bad request line；

5、如果请求是合法的，然后根据请求的uri中的path，寻找是否存在context，参数是 this.protocol, var10.getPath()，如果没有找到path，则抛404异常，核心代码如下：

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 <td> <code>this</code><code>.ctx = ServerImpl.</code><code>this</code><code><a href="https://wiki.youjiayoubao.cn/display/RD/2020/07/27/.contexts.findContext%28" rel="nofollow">.contexts.findContext(</a></code><code>this</code><code>.protocol,&nbsp;<a href="https://wiki.youjiayoubao.cn/display/RD/2020/07/27/var10.getPath%28%29%29;" rel="nofollow">var10.getPath());</a></code> <code>if</code>&nbsp;<code>(</code><code>this</code><code>.ctx ==&nbsp;</code><code>null</code><code>) { </code> <code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>this</code><code>.reject(</code><code>404</code><code>, var3,&nbsp;</code><code>"No context found for request"</code><code>);</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>return</code><code>;</code> <code>}</code> </td> 
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</table>

6、找到HttpContextImpl对象之后，还要校验context是否设置了handler,如果没有配置handler，则抛500错误；

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 <td> <code>this</code><code><a href="https://wiki.youjiayoubao.cn/display/RD/2020/07/27/.connection.setContext%28" rel="nofollow">.connection.setContext(</a></code><code>this</code><code>.ctx);</code> <code>if</code>&nbsp;<code>(</code><code>this</code><code><a href="https://wiki.youjiayoubao.cn/display/RD/2020/07/27/.ctx.getHandler%28%29" rel="nofollow">.ctx.getHandler()</a>&nbsp;==&nbsp;</code><code>null</code><code>) { </code> <code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>this</code><code>.reject(</code><code>500</code><code>, var3,&nbsp;</code><code>"No handler for context"</code><code>);</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>return</code><code>;</code> <code>}</code> </td> 
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</table>

7、然后设置请求的Header和Parameters,初始化ExchangeImpl对象；

8、之后构造Chain对象，执行doFilter方法，doFilter方法的核心就是调用响应的handler方法的逻辑，核心代码如下：

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 <td> <code>List var28 =&nbsp;</code><code>this</code><code><a href="https://wiki.youjiayoubao.cn/display/RD/2020/07/27/.ctx.getSystemFilters%28%29;" rel="nofollow">.ctx.getSystemFilters();</a></code> <code>List var29 =&nbsp;</code><code>this</code><code><a href="https://wiki.youjiayoubao.cn/display/RD/2020/07/27/.ctx.getFilters%28%29;" rel="nofollow">.ctx.getFilters();</a></code> <code>Chain var21 =&nbsp;</code><code>new</code>&nbsp;<code>Chain(var28,&nbsp;</code><code>this</code><code><a href="https://wiki.youjiayoubao.cn/display/RD/2020/07/27/.ctx.getHandler%28%29%29;" rel="nofollow">.ctx.getHandler());</a></code> <code>Chain var22 =&nbsp;</code><code>new</code>&nbsp;<code>Chain(var29,&nbsp;</code><code>new</code>&nbsp;<code><a href="https://wiki.youjiayoubao.cn/display/RD/2020/07/27/ServerImpl.Exchange.LinkHandler%28var21%29%29;" rel="nofollow">ServerImpl.Exchange.LinkHandler(var21));</a></code> &nbsp; &nbsp; <code>//&nbsp; Chain类如下</code> <code>@Exported</code> <code>public</code>&nbsp;<code>static</code>&nbsp;<code>class</code>&nbsp;<code>Chain { </code> <code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>private</code>&nbsp;<code>ListIterator&lt;Filter&gt; iter;</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>private</code>&nbsp;<code>HttpHandler handler;</code> &nbsp; <code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>public</code>&nbsp;<code>Chain(List&lt;Filter&gt; var1, HttpHandler var2) { </code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>this</code><code>.iter =&nbsp;<a href="https://wiki.youjiayoubao.cn/display/RD/2020/07/27/var1.listIterator%28%29;" rel="nofollow">var1.listIterator();</a></code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>this</code><code>.handler = var2;</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>}</code> &nbsp; <code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>public</code>&nbsp;<code>void</code>&nbsp;<code>doFilter(HttpExchange var1)&nbsp;</code><code>throws</code>&nbsp;<code>IOException { </code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>if</code>&nbsp;<code>(!</code><code>this</code><code><a href="https://wiki.youjiayoubao.cn/display/RD/2020/07/27/.iter.hasNext%28%29%29" rel="nofollow">.iter.hasNext())</a>&nbsp;{ </code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>// 执行handle方法，也就是我们实现Handle接口，重写的handle方法</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>this</code><code><a href="https://wiki.youjiayoubao.cn/display/RD/2020/07/27/.handler.handle%28var1%29;" rel="nofollow">.handler.handle(var1);</a></code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>}&nbsp;</code><code>else</code>&nbsp;<code>{ </code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>Filter var2 = (Filter)</code><code>this</code><code><a href="https://wiki.youjiayoubao.cn/display/RD/2020/07/27/.iter.next%28%29;" rel="nofollow">.iter.next();</a></code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code><a href="https://wiki.youjiayoubao.cn/display/RD/2020/07/27/var2.doFilter%28var1," rel="nofollow">var2.doFilter(var1,</a>&nbsp;</code><code>this</code><code>);</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>}</code> &nbsp; <code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>}</code> <code>}</code> </td> 
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</table>

9、如果调用hander方法发生异常时，则调用reject方法，reject方法主要操作氛围两部分，第一是打印错误日志，第二是关闭当前连接，关闭当前连接的操作实质是将存放HttpConnection的Set中remove当前连接对象。

[https_docs.oracle.com_javase_7_docs_jre_api_net_httpserver_spec_com_sun_net_httpserver_HttpExchange.html]: https://docs.oracle.com/javase/7/docs/jre/api/net/httpserver/spec/com/sun/net/httpserver/HttpExchange.html
[20200727220002884.png]: /images/20230208/732a9d7d300b474f9a75390cdae0603d.png
[20200727220059551.png]: /images/20230208/9c462b6bad3c40049550e41fa18ceed2.png